About 25 different kinds of fish could be seen under the 250-meter (820-foot) -long ice circuit. The park in the city of Kitakyushu opened the "Ice Aquarium" as an "attraction never heard about."

Japanese broadcaster NHK showed the fish frozen in ice on a blue floor, so it looked like they were swimming below the ice. Some formed a school to spell out "HELLO" or make an arrow-shaped sign in the ice.

The general manager of Space World, Toshimi Takeda, said many critical messages were posted on social media, some condemning the concept as abusing living things.

Takeda said that the fish in the ice had been intended "to give the feel of the ocean to the ice skating rink," and that the amusement park is "extremely remorseful to have invoked such unpleasant feelings."